1. Field of the Invention
The present invention relates to a technique for managing a session indicative of a logical connection relationship in communication between applications.
2. Description of the Related Art
Conventionally, various kinds of information processing apparatuses including PCs (personal computers), printers, and MFPs (Multi-Function Peripherals) have been known as communication apparatuses for use on a network (an intranet, such as a LAN (Local Area Network) or the Internet).
Today, IP protocols are widely used among information processing apparatuses connected to a network, and under the IP protocols, a unique IP address (communication address) is assigned to each information processing apparatus, whereby connected apparatuses are identified from each other.
In general, under the conventional IP protocols (IPv4 (IP version 4)), a single IP address is assigned to a single network interface as an IP address for identifying one information processing apparatus from others.
On the other hand, under IPv6 (IP version 6), which is recently coming into widespread use, a terminal apparatus communicates with a router upon connection to the same to automatically acquire an IP address. Further, to enable communication even when no router exists, an IPv6 address is assigned on a network interface basis, in addition to the IP address.
Further, a DHCP (Dynamic Host Configuration Protocol) server sometimes exists. In an environment where IPv6 is employed, a plurality of IPv6 addresses are assigned to a single network interface as mentioned above. As a consequence, in an information processing apparatus supporting IPv6, a single network interface is assigned an IPv4 address and a plurality of IPv6 addresses.
In a case where information processing apparatuses communicate with each other, a network socket of a sender of transmission and that of a destination of transmission, i.e. pairs of an IP address and a port number are created. The processing for creating a network socket consumes memory space as the network resource of each information processing apparatus and CPU processing time thereof.
For this reason, a server connected to numerous information processing apparatuses for communication consumes its network resource corresponding in amount to the number of the connections. On the other hand, the amount of network resource available to a printer, an MFP, or the like information processing apparatus is smaller than that of the network resource available to the server, and therefore the number of communication apparatuses that can be connected to the information processing apparatus at the same time is also smaller.
Further, in TCP communication in which a time period taken before opening a network socket is set longer than in UDP communication irrespective of data size, the number of simultaneous connections that can be established per unit time is limited to a smaller value than in UDP communication, and hence a deluge of requests from clients causes a connection error in the server.
To solve this problem, there has been proposed a technique which makes it possible to save network resource in a case where a plurality of applications provided in a client in a client-server system establish a plurality of sessions with a server assigned an identical address, for communication therewith (see Japanese Patent Laid-Open Publication No. H10-177548).
However, when a plurality of IPv6 addresses are assigned to a single network interface, the technique disclosed in Japanese Patent Laid-Open Publication No. H10-177548 is not capable of saving network resource consumed for establishing connections to a plurality of server addresses even in communication with the same server.